Subjects
Fifteen healthy controls were recruited. All were female students enrolled in the master in biomedical sciences at the University of Antwerp (UA). The study was approved by the UA ethics committee and all subjects gave informed consent.
Acquisition
Functional MR images were collected with a 1.5 T scanner (Siemens Sonata, Germany) equipped with 40 mT/m gradients and a standard circularly polarized head coil, using a blood oxygenation level-dependent response (BOLD) sensitive T2* weighted single shot gradient recalled echo (GRE) echo planar imaging (EPI) sequence (TE/TR 50/3000 ms) resulting in voxel dimensions of 3x3x3 mm�.  400 volumes of each 35 slices were thus acquired during both baseline and condition of interest.  In the same scanning session we also recorded a T1-weighted magnetization prepared rapid acquisition gradient recalled echo series (MPRAGE; 1x1x1mm�; TE/TR 3.76/1700 ms) and a T1-weighted spin echo series (SE; 1x1x1,5 mm�; TE/TR 15/700). 
fMRI tasks
Each scanning session consisted of 5 repeated blocks during which subjects were instructed to either rest or perform the PASAT or the PVSAT. Subjects were presented with a sequence of numbers. After each stimulus, starting with the second, subjects had to calculate the sum of the two last stimuli. Subjects were instructed to press a button when this sum was equal to or greater than 10. Both modalities were performed twice in each block, first at a rate of one stimulus per 3 seconds (either visual, V3, or auditory, A3) and afterwards with a rate of once per 2 seconds (either visual, V2, or auditory, A2). Each of the five consecutive blocks was presented as R-V3-R-V2-R-A3-R-A2, where R denotes 30 seconds of rest and A & V denote 30 seconds of either PASAT or PVSAT testing. 
